(1) Field of the Invention
The present invention is a VLF-VHF broadband in-line amplifier. This amplifier is part of a towed buoyant cable antenna system that is deployed in seawater from a submarine. The towed buoyant cable antenna system is comprised of the VLF-VHF broadband in-line amplifier connected between a buoyant antenna element and a buoyant coaxial cable. The buoyant coaxial cable extends inward toward a submarine from the VLF-VHF broadband in-line amplifier.
The VLF-VHF in-line amplifier is designed to operate on the frequencies of interest. These frequencies are those between 10 kHz-160 MHz. The frequencies referred to in the specification are as follows: VLF (very low frequency) 3-30 kHz, LF (low frequency) 30-300 kHz, MF (medium frequency) 300 kHz-3 MHZ, HF (high frequency) 3-30 MHz, and VHF (very high frequency) 30-300 MHz.
(2) Description of the Prior Art
Present amplifiers are capable of only amplifying the higher frequencies. In the VLF/LF range the signals are passed without amplification due to the limitations of the thin film amplifier modules used. Such a system is described by Pease et al. in U.S. Pat. No. 4,760,348 titled Broadband In-Line Amplifier for Submarine Antennas. The Pease et al. system, in which I was a co-inventor also has the problem that it is somewhat complex requiring several miniature inductors and capacitors to separate and combine the DC power and VLF/LF signals with the higher frequencies.